Chamber particle detection system

ABSTRACT

Broadly speaking, the embodiments of the present invention fill the need by providing an improved chamber particle source identification mechanism. The in-situ chamber particle source identification method and apparatus can greatly shorten the time it takes to identify chamber particle source, which could improve the chamber throughput for production system. The method and apparatus can also be used to test components for particle performance during chamber engineering development stage. In one embodiment, an in-situ chamber particle monitor assembly for a semiconductor processing chamber includes at least one laser light source. The at least one laser light source can scan laser light in a chamber process volume within the processing chamber. The in-situ chamber particle monitor assembly also includes at least one laser light collector. The at least one laser light collector can collect laser light emitted from the at least one laser light source. The chamber particle monitor assembly also includes an analyzer external to the processing chamber that analyzes signals representing the laser light collected by the at least one laser light collector to provide chamber particle information.

BACKGROUND

Particle performance is of concern in processing semiconductorsubstrates such as silicon wafers due to reduction in yield caused byparticles adhered to the surface of such substrates. Particles in theprocess chamber that fall on the substrate surface during or aftersubstrate processing can reduce yield. Therefore, it is critical tocontrol particle counts in the process chamber to the minimum to ensuregood yield.

Particles in the process chamber can come from many sources. Processgases and substrate processing can generate particles. Films, eitherfrom process gases or from process byproducts, deposited on thecomponents in the process chamber or on chamber wall(s) can alsogenerate particles. Particles can also be introduced into the processchamber during chamber hardware maintenance by various mechanisms, suchas cleaning solution residues remaining in the chamber when placing thecomponent back into chamber. The O-ring on the chamber gate valve canalso generate particles if the gate valve is clamped too tight or if theO-ring is of poor quality.

Traditionally, particle performance of a process chamber is monitored bymeasuring particle size and number (or count) on a substrate after thesubstrate is processed. The particle performance measurement can be doneregularly to monitor the chamber performance or can be done afterchamber hardware maintenance to qualify the process chamber. If a highparticle count on the substrate is detected, the particle source(s)needs to be identified and the problem(s) needs to be solved beforefurther substrate processing can be continued or before the chamber canbe qualified.

Traditionally, particle source identification is done by running designof experiment (DOE) of various chamber processing and/or hardwareparameters. Substrates processed with the DOE are measured for particleperformance to determine which parameter(s) affects the particle sizeand counts. However, such a particle source identifying process is verylabor and time intensive.

In view of the foregoing, there is a need for a method and apparatusthat provides an improved chamber particle source identificationmechanism to reduce the time and resources used to identify the particlesource(s). The improved chamber particle source identification mechanismcan improve overall chamber particle performance and throughputperformance.

SUMMARY

Broadly speaking, the embodiments of the present invention fill the needby providing an improved chamber particle source identificationmechanism. The in-situ chamber particle source identification method andapparatus can greatly shorten the time it takes to identify chamberparticle source, which could improve the chamber throughput forproduction system. The method and apparatus can also be used to testcomponents for particle performance during chamber engineeringdevelopment stage. It should be appreciated that the present inventioncan be implemented in numerous ways, including as a process, anapparatus, or a system. Several inventive embodiments of the presentinvention are described below.

In one embodiment, an in-situ chamber particle monitor assembly for asemiconductor processing chamber includes at least one laser lightsource. The at least one laser light source can scan laser light in achamber process volume within the processing chamber. The in-situchamber particle monitor assembly also includes at least one laser lightcollector. The at least one laser light collector can collect laserlight emitted from the at least one laser light source. The chamberparticle monitor assembly also includes an analyzer external to theprocessing chamber that analyzes signals representing the laser lightcollected by the at least one laser light collector to provide chamberparticle information.

In another embodiment, a process chamber with an in-situ chamberparticle monitor assembly to identify chamber particle source includes asubstrate support within the process chamber. The process chamber alsoincludes a chamber top plate disposed over the substrate support. Inaddition, the process chamber includes at least one laser light source,wherein the at least one laser light source can scan laser light in achamber process volume within the process chamber and the chamberprocess volume is defined between the substrate support and the chambertop plate. The process chamber also includes at least one laser lightcollector, wherein the at least one laser light collector can collectlaser light emitted from at least one laser light source. Additionally,the process chamber includes an analyzer external to the processingchamber that analyzes signals representing the laser light collected bythe at least one laser light collect to provide chamber particleinformation.

In yet another embodiment, a method of collecting chamber particleinformation in-situ includes scanning laser light emitted from a laserlight source in a process volume inside a process chamber. The methodalso includes collecting the laser light in the process chamber bymultiple laser light collectors. In addition, the method includesanalyzing the collected laser light to determine chamber particleinformation.

Other aspects and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be readily understood by the followingdetailed description in conjunction with the accompanying drawings, andlike reference numerals designate like structural elements.

FIG. 1A shows a schematic cross-sectional diagram of one embodiment ofan in-situ particle detection system in a process chamber.

FIG. 1B shows an embodiment of a top view of the in-situ particledetection system in the process chamber of FIG. 1A.

FIG. 1C shows another embodiment of a top view of the in-situ particledetection system in the process chamber of FIG. 1A.

FIG. 2A shows a schematic cross-sectional diagram of one embodiment ofan in-situ particle detection system in a process chamber with a chamberliner.

FIG. 2B shows an embodiment of a top view of the in-situ particledetection system in the process chamber of FIG. 2A.

FIG. 3 shows a schematic diagram of a chamber volume studied a particledetection system.

FIG. 4 shows a process flow of determining chamber particle informationin a process chamber.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Several exemplary embodiments for an improved and more effective chamberparticle identification system, method and apparatus will now bedescribed. It will be apparent to those skilled in the art that thepresent invention may be practiced without some or all of the specificdetails set forth herein.

As described earlier, the traditionally particle source identificationmethod of running design of experiment (DOE) of various chamberprocessing and/or hardware parameters is very time and resourcesconsuming. Speedy particle source identification is very important inreducing the time it takes to bring the process chamber back intomanufacturing state. An effective in-situ chamber particleidentification method and apparatus can provide instant particleinformation in the process chamber. By reviewing the particleinformation, which could include particle sizes, numbers, and locationsof the particles, particle sources can be revealed or directions forfurther study can be identified. For example, if the chamber particlesare heavily located near the transfer port, the transfer port can besuspected to cause the particle problem. Components of the transferport, such as an O-ring, can be examined or replaced to see if theparticle problem would be resolved. In addition, the operatingparameters of the transfer port can also be studied to test theireffects on the particle problem. For example, the clamping force on thetransfer port door can be reduced to test if the particle problem can bereduced, as clamping the transfer port door too hard can damage theO-ring to cause particle problem.

The direct and instant chamber particle information can greatly shortenthe time it takes to identify chamber particle sources, which couldimprove the chamber throughput for the manufacturing system. Inaddition, the method and apparatus can also be used to test componentsfor particle performance during a chamber engineering development stageto shorten the chamber development time.

One embodiment of the present invention scans laser light by at leastone laser light source into a process volume in the process chamber. Inone embodiment, the process volume is the region above and around thesubstrate support in the process chamber and below the chamber topplate. The process chamber can be any type of process chamber, such aschemical vapor deposition chamber, plasma etching chamber, or thermalvapor deposition chamber, as long as the chamber is enclosed. Theparticles in the region covered (or scanned) by the laser lightsource(s) would reflect the laser light and affect the laser lightpattern in the region studied. A laser is the preferred light sourcebecause its light is a single wavelength (and therefore it is onecolor—typically red or infrared for particle counters). Solid statelaser diodes can be used in one embodiment because of their small size,light weight, and mean time between failures (MTBF).

The laser light can be picked up by at least one laser light detector,such as a photodetector or a camera, installed in the chamber. Aphotodetector is an electric device that is sensitive to light. Anylight that strikes the photodetector causes the photodetector to emit anelectric pulse. The electrical pulses can be analyzed to be correlatedto particle number, sizes and locations. Digital cameras can also beused due to their sensitivity to light. The light detector cancontinuously collect particle data to monitor the chamber particleperformance or can collect particle data only during trouble-shooting.

FIG. 1A shows a cross-sectional view of an embodiment of a processchamber 100 that has a chamber top plate 110, which include a gasdistribution plate (or shower head) 120. In one embodiment, the gasdistribution plate 120 can also be a top electrode for a plasmaprocessing chamber. Chamber 100 also has a substrate support 130 thatcan support a substrate 140. Chamber wall(s) 150 has a substratetransfer port 160 that allows substrate 140 to be transferred in and outof the process chamber 100. Chamber wall 150 could be one piece ormultiple pieces (walls). Laser light source 170 is installed within thechamber wall 150. Laser light source 170 is controlled by a controller175 that control its scanning frequency and direction. In oneembodiment, the laser light source 170 scans across the region 180 aboveand around the substrate support 140. Region 180 is illustrated by thedotted line 185 and corresponds to the chamber process volume. Thesubstrate 140 can be present or not present during the particle sourceidentification process. The laser light is collected by light collector190 that is placed on the chamber wall 150. Since the particles in theprocess chamber would reflect laser light and affect the laser lightpattern, the locations and numbers of the particle in the processchamber can be captured by the laser light collector 190. The laserlight collector 190 is connected to an analyzer 195 to analyze thesignals (or pulses) collected.

The analyzed pulses can be correlated to particle counts, sizes andlocations of the particles in the chamber. If there is only one lightcollector 190 in the process chamber, the particle images collected fromthe chamber would be two-dimensional (2-D). From the particle imagescollected, one can tell the particle counts, particle sizes and in whatdirections relative to the light collector 190 the particles arelocated. In order to get a three-dimensional (3-D) construction ofimages of particles in the process chamber, a plurality of lightcollectors 190 are needed. The plurality of light collectors 190 shouldbe placed such that none of the light collectors share a common axis.

FIG. 1B shows an embodiment of a top cross-sectional view of chamber 100of FIG. 1A with one laser light source 170 and two laser lightcollectors 190 _(I) and 190 _(II). The laser light source 170 scansacross the entire chamber process region 180, whose boundary isillustrated by dotted line 185. The two laser light collectors 190 _(I)and 190 _(II) collect laser light emitted from the laser light source170. The number of particles, size of particles and locations ofparticle in the process chamber region 180 would affect the number andlocations of laser light being reflected. Therefore, the laser lightcollected by the two light collectors 190 can be analyzed by theanalyzer 195 to describe the number, the sizes and 3-D locations of theparticles in the process chamber 100.

In one embodiment, there could be more than one laser light source toensure better coverage of laser light scanning across the chamber 100.FIG. 1C shows an embodiment of a process chamber 100 with 3 laser lightsources 170 and 3 laser light collectors 190. One skilled in the artwill appreciate that other combinations of number of laser light sourcesand laser light collectors are possible.

In addition to mounting the laser light source(s) and laser lightcollector(s) on the chamber wall, the laser light source(s) and thelaser light collector(s) can also be mounted on a chamber liner. In someprocess systems, such as a plasma etch system, the chamber liner(s) isused to reduce film build-up on the chamber wall. Chamber liner could bemade of one piece material, or made of multiple pieces (liners). Detailsof how a chamber liner is installed in a plasma etch chamber isdescribed in U.S. Pat. No. 6,277,237, owned by the Assignee.

FIG. 2A shows a process chamber 100′ that is similar to the chamber 100of FIG. 1A. Chamber 100′ has a chamber liner 155. At least one laserlight source 170 and at least one laser light collector 190 areinstalled on the liner 155. The laser light source(s) 170 scan acrossthe chamber process region 180′, which is slightly smaller than theprocess region 180 of FIG. 1A due to the insertion of the chamber liner155. There is a substrate transfer port 165 on the liner 155 thatmatches with the transfer port 160 on the chamber wall. Since the lineris replaceable, the laser light source(s) and the laser lightcollector(s) can be placed into the chamber when there is a need toidentify particle source. Once the particle problem is solved, the laserlight source(s) 170 and laser light collector(s) 190 can be removed withchamber liner 155, and a new chamber liner 155′ without the laser lightsource(s) 170 and the laser light collector(s) 190 can be placed intothe chamber to continue the manufacturing process.

FIG. 2B shows a top cross-sectional view of chamber 100 with one laserlight source 170′ and two laser light collectors 190 _(I)′ and 190_(II)′, installed on the chamber liner 155. The two laser lightcollectors 190 _(I)′ and 190 _(II)′ enable the construction of 3-Dimages of particles in the process chamber 100 and allows the number,the sized, and 3-D locations of particles in the process region 180′ inthe chamber 100′ to be determined. Similar to laser light source(s) andlaser light collector(s) on the chamber wall, there could be more thanone laser light source to ensure better coverage of laser light scanningacross the chamber process region 180. Different combination of numberof laser light sources and laser light collectors are possible.

FIG. 3 shows an exemplary 3-D schematic drawing of region 180 surroundedby dotted boundary lines 185. The laser light pattern collected by thelaser light collector(s) 190 of FIG. 2B shows a large amount ofparticles near the chamber transfer port 160. Based on the particleinformation illustrated in FIG. 3, further particle study on thetransfer port 160 can be conducted. Additional analysis can lead to theconclusion that the transfer port O-ring releases large amounts ofparticles due to the transfer port door being clamped too tight andresulting in O-ring damage. By viewing the 3-D chamber particle imagesas a function of time, the origin and the movement of particles can alsobe traced. The 3-D images can be very useful in speeding up the chamberparticle source identification.

FIG. 4 shows a process flow of using the chamber particle detectionsystem to detect particles in a process chamber. The process 400 startsat step 410 by scanning laser light in a process volume. In oneembodiment, the process volume is defined between a chamber top plateand a substrate support, where the laser light is provided by one ormore laser light sources. The process is then followed by collectinglaser light in the process chamber from the process volume using atleast one laser light collector at step 420. If three-dimensionalchamber particle information is to be collected, there needs to be atleast two laser light collectors. The at least two laser lightcollectors should be placed apart from each other and not directlyopposite of each other. After the laser light is collected by the laserlight collectors, the signals are analyzed by an analyzer to determinethe chamber particle information at step 430.

The chamber particle information includes the particle counts, particlesizes, particle size distribution, and locations of the particles. Byreviewing the pattern of particles distributed in the process chamber,the source(s) of particles can be revealed or direction of further studycan be identified.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalents of the appended claims.

1. An in-situ chamber particle monitor assembly for a semiconductorprocessing chamber, comprising: at least one laser light source, whereinthe at least one laser light source can scan laser light in a chamberprocess volume within the processing chamber; at least one laser lightcollector, wherein the at least one laser light collector can collectlaser light emitted from the at least one laser light source; and ananalyzer external to the processing chamber that analyzes signalsrepresenting the laser light collected by the at least one laser lightcollector to provide chamber particle information.
 2. The in-situchamber particle monitor assembly of claim 1, wherein the chamberparticle information comprises particle number, particle sizes andlocations of particles.
 3. The in-situ chamber particle monitor assemblyof claim 1, wherein there are a plurality of laser light collectors, theplurality of laser light collectors are placed such that none of theplurality of laser light collectors share a common axis.
 4. The in-situchamber particle monitor assembly of claim 3, wherein the chamberparticle information include three-dimensional image representingparticle distribution within the chamber process volume.
 5. The in-situchamber particle monitor assembly of claim 1, wherein at least portionsof both the at least one laser light source and the at least one laserlight collector are embedded within a chamber wall.
 6. The in-situchamber particle monitor assembly of claim 1, wherein at least portionsof both the at least one laser light source and the at least one laserlight collector are embedded within a chamber liner.
 7. The in-situchamber particle monitor assembly of claim 1, wherein the chamberprocess volume encompasses a plane defined above a substrate supportwithin the process chamber.
 8. A process chamber with an in-situ chamberparticle monitor assembly to identify chamber particle source,comprising: a substrate support within the process chamber; a chambertop plate disposed over the substrate support; at least one laser lightsource, wherein the at least one laser light source can scan laser lightin a chamber process volume within the process chamber and the chamberprocess volume is defined between the substrate support and the chambertop plate; at least one laser light collector, wherein the at least onelaser light collector can collect laser light emitted from at least onelaser light source; and an analyzer external to the processing chamberthat analyzes signals representing the laser light collected by the atleast one laser light collect to provide chamber particle information.9. The process chamber of claim 8, wherein there are a plurality oflaser light collectors, the plurality of laser light collectors areplaced such that none of the plurality of laser light collectors share acommon axis.
 10. The process chamber of claim 8, wherein there are atleast two laser light sources, the at least two laser light sources areplaced apart from one another to provide light sources to the processchamber.
 11. The process chamber of claim 8, wherein at least portionsof both the at least one laser light source and the at least one laserlight collector are embedded within a chamber wall.
 12. The processchamber of claim 8, wherein a chamber wall is defined around thesubstrate support and a liner is disposed within the chamber wall. 13.The process chamber of claim 12, wherein at least portions of both theat least one laser light source and the at least one laser lightcollector are embedded within the chamber liner.
 14. The process chamberof claim 12, wherein there are a plurality of chamber liners and atleast portions of both the at least one laser light source and the atleast one laser light collector are embedded within the plurality ofchamber liners.
 15. The process chamber of claim 13, wherein there are 3laser light sources and 3 light source collectors.
 16. A method ofcollecting chamber particle information in-situ, comprising: scanninglaser light emitted from a laser light source in a process volume insidea process chamber; collecting the laser light in the process chamber bymultiple laser light collectors; and analyzing the collected laser lightto determine chamber particle information.
 17. The method of claim 16,wherein the process volume is defined between a chamber top plate and asubstrate support.
 18. The method of claim 16, further comprises:orienting the multiple laser light collectors such that none of themultiple laser light collectors share a common axis.
 19. The method ofclaim 16, further comprises: embedding the laser light source and themultiple laser light collectors within a chamber wall.
 20. The method ofclaim 16, further comprises embedding the laser light source and themultiple laser light collectors within a chamber liner.
 21. The methodof claim 20, wherein the chamber liner with the laser light source andmultiple laser light collectors are removable.
 22. The method of claim16, wherein the chamber particle information includes particle size anddistribution and particle location information within the processchamber.
 23. The method of claim 16, wherein the analyzing the collectedlaser light includes generating a 3-D image representing particledistribution inside the process chamber.
 24. The method of claim 23,wherein the 3-D image includes particle size information.